Injectable Superparamagnets: Highly Elastic and Degradable Poly(N‑isopropylacrylamide)–Superparamagnetic Iron Oxide Nanoparticle (SPION) Composite Hydrogels

• Published in: Biomacromolecules 2013-03, Vol.14 (3), p.644-653
• Main Authors: Campbell, Scott B, Patenaude, Mathew, Hoare, Todd
• Format: Article
• Language: English
• Subjects: Acrylamides - chemistry; Acrylic Resins; Animals; Applied sciences; Biocompatible Materials - chemistry; Biological and medical sciences; Capsules; Composites; Elasticity; Exact sciences and technology; Ferric Compounds - chemistry; Forms of application and semi-finished materials; Gels - chemistry; General pharmacology; Hydrogels - chemistry; Hydrogen-Ion Concentration; Injections; Magnetite Nanoparticles - chemistry; Medical sciences; Mice; Mice, Inbred BALB C; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Polymer industry, paints, wood; Polymers - chemistry; Technology of polymers; Temperature; Tissue Engineering - methods
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm301703x

Injectable, in situ-gelling magnetic composite materials have been fabricated by using aldehyde-functionalized dextran to cross-link superparamagnetic nanoparticles surface-functionalized with hydrazide-functionalized poly(N-isopropylacrylamide) (pNIPAM). The resulting composites exhibit high water contents (82–88 wt.%) while also displaying significantly higher elasticities (G′ >60 kPa) than other injectable hydrogels previously reported. The composites hydrolytically degrade via slow hydrolysis of the hydrazone cross-link at physiological temperature and pH into degradation products that show no significant cytotoxicity. Subcutaneous injections indicate only minor chronic inflammation associated with material degradation, with no fibrous capsule formation evident. Drug release experiments indicate the potential of these materials to facilitate pulsatile, “on-demand” changes in drug release upon the application of an external oscillating magnetic field. The injectable but high-strength and externally triggerable nature of these materials, coupled with their biological degradability and inertness, suggest potential biological applications in tissue engineering and drug delivery.